Roof structure



J. P- SHEAHAN ROOF STRUCTURE Nov. 1, 1966 Filed Feb. 14, 1963 u If H AlINVENTOR. James P 'fzeczkazz QQ LM J. B

3,282,608 RQQF STRUCTURE James Patrick Sheahan, Midland, Mich assignorto The Dow Chemical Company, Midland, Mich, a corporation of DelawareFiled Feb. 14, 1963, Ser. No. 258,584 5 Claims. (Cl. 52-516) Thisinvention is directed to the problem of reducing the flow of combustibleroofing materials through an insulated roof structure, in case of aninternal fire. A fire in a roofed area can be drastically increased byflow of combustible roofing materials such as asphalt melted by thefire-into the roofed area.

The present invention solves the problem in a simple, but effectivemanner, by providing a filter effect which regulates the flow of anysuch combustible roofing materials to a rate so low, that fireintensity, or propagation is not increased. Briefly, the inventiveconcept includes the use of a fire resistant sheet material between theroof deck and the roofing material, the latter of which may include alayer of thermal insulation. The fire resistant material selected, willact as a filter which regulates the flow of combustible materialsthrough the roof deck.

The main object of this invention is to provide a method andconstruction which functions to prevent intensity increase, orpropagation of a fire in a roofed area as a result of melted roofingmaterials flowing into the fire.

A more specific object is to provide a fuel barrier to roofing materialsfor internal fires, whereby the flow of melted combustible reefingmaterials into the fire is regulated to such a low rate as not tosubstantially increase the intensity, or propagation of the fire.

A further object is to provide an insulated roof structure, including afuel barrier, which structure is easily formed of materials readilyavailable in the market.

These and further objects and features of the invention will be moreapparent from the following description and accompanying drawingwherein:

FIG. 1 is a perspective-like fragmentary view of a roof structure formedin accordance with the method of the invention; and FIG. 2 is anenlarged section view taken through the roof structure of FIG. 1.

Referring now to the drawing, numeral 6 identifies a roof structureembodying the principles of the invention, which structure is supportedupon girders 8, the ends of which may be secured to walls ill (oneshown) of a building. The roof structure inludes a metal deck 12, coatedover its entirety with a fire resistant adhesive 14, upon which is laida non-combustible sheet 16, which is not impervious to water vapor. Thesheet 16 may be formed of asbestos felt (saturated in conventionalmanner with asphalt-usually 9 lbs. asphalt per 100 sq. ft. of felt oreven non-saturated), flame retardant impregnated paper sheet, glasscloth, intumescent coating on asbestos, perforated metal foil or foilpaper laminates. A waterproofing substance, such as a hot steep asphalt18 (190 F. melt) is applied to the sheet 16, and blocks, or sheets 20 ofa closed cell insulation, such as expanded polystyrene or polyurethane,are laid directly upon the hot asphalt 18 while still in tackycondition. The insulation thickness will be in accordance with thermalrequirement, however, thicknesses in a range of from /1" to 2%" willsuifice for most purposes. Finally, a 4 ply standard asphalt built-uproof 22 is applied directly upon the insulation 26, using a coated basesheet as the first ply. FIG. 2 illustrates in cross-section theresulting roof structure.

The non-combustible sheet 16 will regulate the flow of melted roofproducts during a fire so that the fire is not intensified or propagatedby these products, and further, will allow the free passage of moisturevapor thus preventing blistering of the roof. Design objectives will, ofcourse, dictate specifications of the materials being used, however, ahighly successful roof structure was formed with a rubber basenon-flammable adhesive i4 known as Reflecto Barrier 77", sold by theRefiecto Barrier Sales Co. of Hartford, Connecticut applied at a rate of0.4 of a gallon per sq. ft., an asbestos sheet 16 of 30 lb./ 100 sq. ft.weight, and the asphalt 18, applied at a rate of 10 lbs. per 100 sq. ft.

It will be seen that a roof structure made as above described willsatisfy all of the objectives of the invention.

The foregoing description has been given in detail without thought oflimitation since the inventive principles involved are capable ofasusming other forms without departing from the spirit of the inventionor the scope of the following claims.

What is claimed is:

1. An improved roof structure which functions to prevent intensityincrease and propagation of a fire under said roof structure as a resultof melted roofing materials flowing into said fire, comprising incombination, a roof deck, a continuous coating of rubber base fireresistant adhesive on said deck, a non-combustible watervapor pervioussheet adhered by said adhesive to said deck and completely covering saiddeck, a coating of waterproof substance completely covering said non-combustible sheet and adhered thereto, a layer of thermoinsulating materialadhered to the top of said coating of waterproof substance and at leastone layer of roofing material completely covering and adhered to saidinsulating material.

2. The improved roof structure of claim 1 wherein said non-combustiblesheet comprises asbestos felt.

3. The improved roof structure of claim 1 wherein said non-combustiblesheet comprises asbestos with an intumescent coating.

4. The roof structure of claim 1 wherein said noncombustible sheetcomprises perforated metal foil.

5. The roof structure of claim 1 wherein said noncombustible sheetcomprises a flame retardant impregnated paper sheet.

References Cited by the Examiner UNITED STATES PATENTS 1,606,496 11/1926Beckwith et al. 52516 2,122,747 7/ 1938 Kirschbraun 52-3 02 2,373,3174/1945 Lawson 52516 2,848,957 8/1958 Babcock 52516 3,041,219 6/ 1962Steck.

3,094,447 6/ 1963 Chamberlain.

3,111,787 11/1963 Chamberlain 52173 3,135,069 6/1964 Schuller et al.52-77 FOREIGN PATENTS 549,059 11/ 1942 Great Britain.

EARL J. WITMER, Primary Examin r.

1. AN IMPROVED ROOF STRUCTURE WHICH FUNCTIONS TO PREVENT INTENSITYINCREASE AND PROPAGATION OF A FIRE UNDER SAID ROOF STRUCTURE AS A RESULTOF MELTED ROOFING MATERIALS FLOWING INTO SAID FIRE, COMPRISING INCOMBINATION, A ROOF DECK, A CONTINUOUS COATING OF RUBBER BASE FIREBESISTANT ADHESIVE ON SAID DECK, A NON-COMBUSTIBLE WATER VAPOR PERVIOUSSHEET ADHERED BY SAID ADHESIVE TO SAID DECK AND COMPLETELY COVERING SAIDDECK, A COATING OF WATERPROOF SUBSTANCE COMPLETELY COVERING SAIDNON-COMBUSTIBLE SHEET AND ADHERED THERETO, A LAYER OF THERMOINSULATINGMATERIAL ADHERED TO THE TOP OF SAID COATING OF WATERPROOF SUBSTANCE ANDAT LEAST ONE LAYER OF ROOFING MATERIAL COMPLETELY COVERING AND ADHEREDTO SAID INSULATING MATERIAL.